The objectives of this project are twofold: (1) Partial purification and characterization of the increased proteolytic activity associated with high metastatic potential mouse melanoma cells and determination of its role in the production of metastasis. (2) Characterization of the cyclic nucleotide system in mouse melanoma cells of low and high metastatic potential both in vitro and in vivo and attempts to suppress metastasis in vivo by manipulating the cyclic nucleotide system of high metastatic potential melanoma cells. The goals set for the first year of this grant were to repeat our prior observations on the increased proteolytic activity of high metastatic potential mouse melanoma cells. An adjunct to this goal was to develop a reproducible and sensitive proteolytic assay system. Another goal for the first year of this grant was to characterize the hormonal responses of the mouse melanoma lines of varying metastatic potential in relation to their ability to increase intracellular cyclic AMP levels.